workaholic
Definitions
A person who compulsively works excessively hard and for long hours.
A person who is unable to refrain from excessive work, often at the expense of their personal life or health.
Examples
My manager is such a workaholic that she often sends emails at three in the morning.
He realized he was becoming a workaholic when he started missing his children's soccer games to finish projects.
Synonyms
overachiever eager beaver grindstone enthusiast industrious person work-obsessed individual